GROWTH, DEVELOPMENT, AND PHOTOSYNTHETIC PERFORMANCE OF TWO SOYBEAN LINEAGES IN RESPONSE TO DROUGHT

Drought stress is a common environmental factor that constrains plants from expressing their ecophysiological potential, disrupting various physiological and biochemical processes. Hence, the objective of this work was to evaluate the growth, development and photosynthetic performance under drought in the vegetative phenological stage of soybean in two lineages with potential difference tolerance to this abiotic stress, lineages (‘Vx-08-10819’ and ‘Vx-08-11614’. For this purpose, biometric traits of development, relative water content in leaves, photosynthetic pigments, gas exchange, and chlorophyll a fluorescence were evaluated. The experimental design was a randomized block design with 4 replications and arranged in a 2 × 3 factorial scheme, comprising of two soybean lineages (Vx-08-10819 and Vx-08-11614) in combination with three water availability [100% (control), 60%, and 40% of field capacity]. Relative water content in leaves, total leaf area, and shoot dry weight of lineage Vx-08-10819 were not changed after exposure to drought. Besides that, photosynthetic capacity of lineage Vx-08-10819 was less affected than lineage Vx-08-11614 to drought, showing that this lineage is tolerant to this abiotic stress in at vegetative stage V4. Keywords: chlorophylls; gas exchange; Glycine max (L.) Merr; water relations. Crescimento, desenvolvimento e desempenho fotossintético de duas linhagens de soja em resposta à seca RESUMO: O estresse hídrico é um fator ambiental comum que impede as plantas de expressarem seu potencial ecofisiológico, interrompendo vários processos fisiológicos e bioquímicos. Portanto, o objetivo deste trabalho foi avaliar o crescimento, o desenvolvimento e o desempenho fotossintético sob seca na fase fenológica vegetativa da soja em duas linhagens com potencial diferença na tolerância a este estresse abiótico, as linhagens Vx-08-10819 e Vx-08-11614. Para tanto, foram avaliadas características biométricas de desenvolvimento, teor relativo de água nas folhas, pigmentos fotossintéticos, trocas gasosas e fluorescência da clorofila a. O delineamento experimental foi em blocos casualizados com 4 repetições e dispostos em esquema fatorial 2 × 3, composto por duas linhagens de soja (Vx-08-10819 e Vx-08-11614) em combinação com três disponibilidades hídricas [100% (controle), 60% e 40% da capacidade de campo]. O conteúdo relativo de água nas folhas, a área foliar total e o peso seco da parte aérea da linhagem Vx-08-10819 não foram alterados após